The FDA recently approved tucatinib, in combination with trastuzumab and pertuzumab, as a maintenance treatment for patients with HER2-positive breast cancer, according to a press release issued by the agency.

The approval applies to patients with unresectable locally advanced or metastatic disease.

The agency based its decision on data from the HER2CLIMB-05 study, a phase 3 clinical trial of patients with locally advanced or metastatic HER2-positive breast cancer. Enrollment was permitted for patients who demonstrated no evidence of disease progression after induction therapy with trastuzumab, pertuzumab, and taxane therapy.

In the randomized controlled study, the researchers randomly assigned patients to oral tucatinib (300 mg twice daily) or placebo. Trastuzumab and pertuzumab were either administered intravenously together, or subcutaneously along with hyaluronidase.

The study met its primary endpoint, demonstrating a statistically significant and clinically meaningful improvement to progression-free survival (PFS) for patients assigned to tucatinib. Compared to placebo, the tucatinib-based combination correlated with a 35.9% reduction in the risk for disease progression or death.

The median PFS for patients assigned to tucatinib was 24.9 months, compared with 16.3 months for placebo.

Overall survival served as an additional efficacy outcome measure, but data were not mature at the time of reporting.

Treatment with tucatinib resulted in an increased risk for hepatotoxicity, with a boxed warning issued by the FDA. The researchers noted the majority of hepatotoxicity events were asymptomatic and reversible.

Commonly observed adverse events included diarrhea, musculoskeletal pain, hepatotoxicity, nausea, fatigue, rash, and vomiting. One patient died due to drug-induced liver injury.

“Since its first approval in 2020, [tucatinib] has become an important treatment for patients with second-line HER2+ metastatic breast cancer. Today's FDA approval marks the next chapter for [tucatinib], bringing it into the front-line maintenance setting and offering patients a chemotherapy-free option that can help delay disease progression after initial treatment.”

- Aamir Malik, executive vice president and chief US commercial officer at Pfizer

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By Cameron Kelsall 

Disclosures: The HER2CLIMB-05 study was funded by Pfizer. Malik is an employee of Pfizer.

References:

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-tucatinib-trastuzumab-and-pertuzumab-maintenance-treatment-her2-positive-breast-cancer

https://www.pfizer.com/news/press-release/press-release-detail/pfizers-tukysa-regimen-receives-fda-approval-front-line

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